After consulting with Google for at least an hour i finally hit upon a page that helped me.

I found the answer in the following howto Postfix w/o Maildrop. The authdaemon socket setup described on this page was slightly different to the usual suggestions (most help I found online suggested to create a hardlink to the socket file inside the Postfix chroot, this doesn’t work for Ubuntu cause the /var/run is on a different filesystem and a symlink didn’t work for me either). The following commands were taken directly from the howto listed above (all credit should go to the writer of that page).

Thanks, my night was saved either.
After reboots this structure seem to break again. At least at my virtual server.
Any ideas?
I put this little script in the rc.local, but I would like to know the cause…